Mosquito-borne diseases (MBDs) are an increasing global public health concern. The increase of international human activities and the global warming, have allowed the rapid spread and establishment of invasive mosquito species in new geographical areas. Moreover, the globalization also cause the introduction of exotic arboviruses in naïve areas where the mosquito vector is present, enhancing MBDs outbreaks.
The outbreaks of MBDs, especially those caused by arbovirus like Dengue virus, Zika virus (ZIKV), Rift Valley fever virus (RVFV) or West Nile virus (WNV), have severe consequences for public and/or veterinary health. The economic losses linked to the zoonotic MBDs can severely compromise the economy of the affected country. This is particularly relevant in the developing countries, where diseases such as Rift Valley fever can provoke the death of a huge number of domestic and wild animals. For these reasons a deep knowledge of which mosquito species are present in a country and which of them are competent vectors of different pathogen agents is needed in order to set up appropriate surveillance programs and entomological control strategies.
The present thesis is divided in three parts and each one is further divided in chapters.
The first part consists of two sections: Chapter 1- General Introduction and Chapter 2- Objectives. The aim of this first part is to give a general overview on the importance of MBDs, the role of the vectors and the concept of vector competence. The descriptions of WNV and RVFV are also provided. Afterwards, the objectives of the thesis are exposed. So far, the population dynamics and the genetic structure of invasive Aedes albopictus, the Asian tiger mosquito, were unknown in Spain. Moreover, no studies on the vector competence of Spanish populations of Culex pipiens and Ae. albopictus for zoonotic arboviruses (WNV and RVFV) have been performed until now. The aim of the present thesis is to clarify all these points.
The second part is formed by three chapters. Each of them is an original study aimed to answer the objectives.
In the first study (Chapter 3), the genetic structure of Ae. albopictus in Spain has been analyzed with the use of different genetic tools. Based on the results obtained, two different hypotheses have been postulated to explain the introduction and the spread of this species across the country. Moreover, a global analysis about the worldwide spread of Ae. albopictus has been performed. The results of both analyses confirmed the importance of human activities for the local and global dispersion of Ae. albopictus.
The second and third studies (Chapter 4 and Chapter 5, respectively), demonstrated how Spanish Cx. pipiens and Ae. albopictus are competent vectors for WNV and RVFV. In both studies the importance of using variable cycling temperature during the extrinsic period of incubation have been verified. The results suggested that variable cycling temperature allows to estimate a more realistic vector competence. Moreover, different approaches have been used for the detection of viral particles in the saliva of infected mosquitoes.
The third includes Chapter 6- General discussion and Chapter 7- Conclusions. In this part all the findings are discussed, further studies are proposed and the major conclusions are detailed.
At the end of each chapter all the references used are listed.